Electrostatic discharges may cause permanent damage to electronic circuits. Semiconductor integrated circuits are particularly susceptible to electrostatic discharge. Therefore, protection elements or structures are required to protect, for example, analog or digital data lines of semiconductor integrated circuits. The ideal electrostatic discharge protection element immediately shunts any voltage which has a magnitude above a predefined critical threshold, and does not affect the characteristics of the data line during normal operation, i.e., for voltages below the threshold value. General objects of a design for electrostatic discharge devices are: keeping the peak voltage at the beginning of an electrostatic discharge occurrence or pulse at a minimum; keeping the degradation for a large number of electrostatic discharge occurrences at a minimum to ensure a long product life time; and providing a high insulation for low frequencies during normal operation.
Known protection elements are, for example, polymer protection elements or high quality coils. The polymer protection elements and the coils show a high peak voltage in case of electrostatic discharges. In addition, the polymer protection elements show degradation after many electrostatic discharge pulses and the coils show a poor isolation at low frequencies, i.e., a certain conductivity at low frequencies against ground during normal operation.
Equal or equivalent elements or elements with equal or equivalent functionality are denoted in the following description by equal or equivalent reference numerals.